The value of the ability to acquire, interrogate and display n-dimensional data sets has been well established through various scientific disciplines. The biomedical sciences, in particular, have developed sophisticated methods to visualize volumetric image data. However, 3D tomographic data acquisition and volume visualization through the application of serial FIB (Focused Ion Beam) sectioning has only just begun to emerge as a demonstrable method, with work completed by a small number of researchers. The FIB-SEM and FIB-Auger tomographic methods have demonstrated the ability to provide volumetric data resolution down to 10 nm or less, and thus hold tremendous future potential for both material science and biomedical investigations. Yet even the best examples of what have been accomplished thus far in the field of FIB-based nanotomography reflect the fact that this technique is still in the early stages of its development. Regarding prior art in FIB-SEM tomographic methods reference is made to Chapter 14 (Robert Hull) and Chapter 15 (E. L. Principe) and references contained therein, in “Introduction to Focused Ion Beams: Instrumentation, Theory, Techniques and Practice” Giannuzzi, Lucille A.; Stevie, Fred A. (Eds.); Springer-Verlag (2004).
Factors that limit wider utilization of FIB-based tomographic methods include the ease, speed and density of raw data collection. Another obstacle is implementing robust, yet versatile data analysis and volume visualization methods suitable for electron imaging. In principle, the hardware exists for over a decade to collect volumetric image data from a set of sequential FIB serial sections. Yet FIB-based nanotomography has, until now, remained a less practical application due to the time, effort and specialized data reduction expertise involved.
The methods of quantifying cross sectional slices obtained by FIB disclosed until now require either a measurement of each frame image perpendicularly to its cross section to measure the thickness of the material removed or another method to quantify based upon the cross sectional images. The first method requires, however; either achieving a perpendicular view through another image recording system and/or moving the sample to achieve the perpendicular view.
More recently, for example, in U.S. Pat. No. 6,855,938, systems have been disclosed which can be used for FIB-SEM tomographic methods.